Add these to your php.ini, or other .ini files, as global options for PHP-Error.
The standard php.ini setting, display_errors, is required to be on for PHP Error to work. Otherwise it silently does nothing.
display_errors = On
This is a safety feature, as it's turned off in lots of production setups.
When set to 'on', the error reporter will look and act like it's running, but really it does nothing. No setup changes, no error reporting, and no other work.
php_error.force_disabled = On
If you manually call 'turnOn', it on will also silently fail, and still be set to turned off.
My advice is to never put PHP-error into production. This option exists incase you forget, so you can disable it for all of your sites as a part of your global configuration.
When to to 'on', PHP Error will be run automatically, without you having to call it manually in your site.
php_error.autorun = On
This is useful for keeping it outside of a project, so you can easily deploy the project without including PHP Error.
The settings from the options section can be set in php.ini to alter their defaults. This is useful when using it with autorun, or to provide bespoke defaults.
To use, just add the option with the prefix 'php_error.' before it.
For example to turn off 'catch_ajax_errors' and change the 'snippet_num_line' value, you would add to your php.ini file:
php_error.catch_ajax_errors = Off php_error.snippet_num_line = 20